A portable electronic device has been highlighted in many fields of an industry and a life since it is small enough to carry while supporting a specific user function. In recent years, a portable electronic device integrally supporting various user functions has been appeared. Accordingly, a configuration of portable electronic device has been added, and a performance of central processing unit (CPU) of the portable electronic device has been improved in order to control the added configuration.
On the other hand, as the performance of CPU of the portable electronic device is improved, an electric power load of CPU is increased, and accordingly, a magnitude of a battery voltage drop of the portable electronic device is also increased. In addition when a battery voltage drops, a voltage, which is required for operation of a system such as an embedded Multi-Media Card (eMMC) and a CPU, may not be supplied.